1. Technical Field
This invention relates to BIOS interfaces. In particular, a BIOS interface for controlling video features of a system.
2. Background Art
A Liquid Crystal Display (LCD) is a commonly used peripheral (I/O) device on computer systems. Due to the nature of the LCD hardware, it is important to have the contrast and backlight properly adjusted to enable a user to read the LCD display screen comfortably. However, in commercial settings terminals may be unattended for long periods of time. This is disadvantageous because the useful life of the display is a function of backlight use. For example, the mean time between failure (MTBF) of the LCD screen is greater than that of a CRT display, but the MTBF of the backlight is less than that of a CRT display. Therefore, the ability to control usage of the backlight directly effects the relative reliability of an LCD display in relation to a CRT display. In turn, this effects the decision of a purchaser when reliability is an issue. It would be desirable to have a simple way to automatically control the backlight with software to avoid unnecessary wear on the backlight.
In addition, in systems with multiple displays, switching from one display to another involves a complicated software process. Typically a prior art system will have to do the following to switch displays:
1. Save the BIOS interrupt vectors and BIOS data areas of the currently selected video port.
2. Change hardware registers to deselect one port and select another.
3. Restore the interrupt vectors and BIOS data area of the newly selected video port.
In summary, the reliability of LCD terminals is not as good as the hardware will allow. In addition, control of display switching is inefficient. The prior art has not shown the ability to easily and efficiently control LCD hardware displays.